John;
You say your gun has 11 on one bbl & 12 on the other. Do they just have the single mark & not the dual marks with one having a B & the other an M following? It must be remembered that until the general acceptance of choke boring even breech loaders were measured by the process which had been developed during muzzle loader days, ie measured from the muzzle. Since your gun bears the stamp "Not for Ball" it would indeed indicate it was choked. While theoretically the not for ball & the dual markings for bore & muzzle came in together, it is quite conceivable some one simply marked it by the "Old Rule" & stamped muzzle dia & then added the Not for Ball realizing it was choked. In the vast majority of cases though it can be assumed if there is only a single size mark per bbl it is to be taken as bore dia, not choke. I do not think I have ever heard of a case where bore size was marked on one bbl & choke size on the other one. There are guns with the dual marking on one bbl & a single mark on the other. The bbl carrying only the single mark will be found to be cylinder, the other choked.
